SMOES - A SIMULATION-MODEL FOR THE OOSTERSCHELDE ECOSYSTEM .2. CALIBRATION AND VALIDATION

SMOES is an invalid model in the Popperian sense of the word. Yet it m ight be a useful model, which accurately simulates some of the ecosyst em behavior. Our knowledge of the Oosterschelde ecosystem is empirical and consists of a comprehensive set of observed data (experiments and in situ measurements). Model usefulness will be investigated in terms of model adequacy (can a model simulate all system behavior) and reli ability (does it simulate observed system behavior only). The large im pact of the building of a storm-surge barrier in the Oosterschelde Mou th (compartment West) allows us to distinguish two different systems. The quality of the simulation model, built and calibrated for the pre- barrier system, can so be tested by using it for the (new) post-barrie r system. The question if the model does predict the post-barrier futu re will be answered. We apply a calibration method which generates not merely a single best value for each of the many badly known parameter s, but which also enables us to estimate the uncertainty in the model outcome. If we use this method to calibrate SMOES for the pre- and for the post-barrier situation, and subsequently estimate the uncertainty in the model results, we find no large (functional) shifts in the beh avior of the main ecosystem properties.